TAB bonding is well known in the semiconductor arts. A semiconductor die for TAB bonding includes metal bond pads disposed on a surface thereof. A TAB lead tape includes a flexible insulating film such as a polyimide having a metal conductive pattern formed on the insulating material. The metal conductive pattern includes lead portions which are coupled directly to the metal bond pads disposed on the surface of the semiconductor die. In employing TAB bonding, no wire bonding is necessary.
It is also well known in the semiconductor arts to encapsulate semiconductor devices. Encapsulation is typically performed with a polymer, plastic or similar material. The encapsulation most often surrounds the entire semiconductor die. The encapsulation protects the die from moisture and contaminants as well as providing physical protection.
Encapsulating semiconductor devices in plastic and similar materials has various disadvantages. Since the encapsulating material completely encapsulates the semiconductor device, plastic encapsulated packages are often relatively thick. The thickness of these packages includes the sum of the thicknesses of the semiconductor die, the encapsulation disposed on top of the semiconductor die and the encapsulation disposed beneath the semiconductor die. In wire bonded packages, this thickness also includes the height of the wire bonds. In TAB bonded packages where the bond pads are of a significantly lower height than wire bonds, this is not a significant problem.
Encapsulated semiconductor devices generally have poor thermal dissipation properties. When heat is given off by the semiconductor die, it typically must then dissipate through the encapsulation. Well known encapsulation materials do not dissipate heat adequately. The heat dissipation problem is somewhat improved by the addition of heatsinks to encapsulated packages. However, when heatsinks are encapsulated as is well known in the art, the heat must still dissipate through the encapsulation. Packages having an exposed heatsink are also well known in the art. The exposed heatsink dissipates heat adequately in some applications although it is not optimum. A semiconductor die is typically attached to a heatsink using glass filled die attach material. Whenever a semiconductor die is attached to a heatsink, a certain amount of thermal conductivity is lost between the die and the heatsink and thermal dissipation suffers.
Accordingly, it would be highly desirable to have an encapsulated semiconductor package that is relatively thin, has excellent thermal dissipation properties, adequately protects the semiconductor die from moisture and contaminants and is relatively inexpensive to manufacture.